Re: Still Trying.. (One Last Shot pt2)
If the vehicle is in fact in an ignition misfire, you should expect the AFR to show lean (and tyypically the O2 crosscounts to start increasing. You can't rely on the O2 sensors to give you remotely correct information at this point. The unused Oxygen passing through the exhaust would "fool" the sensors.
How does the vehicle run in bypass timing mode. Power will obviously be down, but does it misfire?
During your spark tests, you should be removing the wire and then grounding it (or use a spark checker set at low kV. The huge spark requirement you are giving it is begging for your max spark kV (30kV or higher on a stock coil, over 60kV on a good aftermarket coil) to find a new home (through the wire). Once it's through the wire, you should be replacing that wire, it's insulation has been compromised. I wouldn't read anything into the coil arcing while in that open wire condiiton, but I also couldn't see your video since Photobucket site is down.
I couldn't see (and did not read your first post-it's already past my bedtime) if you have EGR connected and if you removed/plugged it to see if it changes. It seems like it's one of the first things to go, so it's probably already long gone...)
Things are so much easier with a scope, but let me run this situation by you: While Fuel Pressure is raised, the current requirement to open the injector is low. As you increase Fuel Pressure, that current requirement is raised. A poor injector ground circuit ( C13 and D7) could cause such problems. I realize it doesn't take into account why it only happens at certain loads, but no offense, but I can't tell much from your descriptions, outside of a laundry list of parts that have been changed out. I have dealt with this for over a decade in the automotive industry- "Fuel pressure? Yah, it's good. Grounds? Yep, added some and cleaned them all up.." Unfortunately that doesn't answer much. Without a scope you can use a meter to VERIFY correct powers and grounds (both running well and "acting up". Voltage falling on the power side? Voltage RISING on the ground side?
What are the fuel pressures you are running? Maybe I missed it, but I only see "okay"?
A common enough issue with GM vehicles is the stator shaft magnet cracks at the rivets and the resulting signals can indicate far more rpm than the engine is running at. It would really screw with your spark/injector firing and could be more sensitive to RPM than many of the other items that could fail.
You do have your scope yet? Feel free to PM me and I can run you through your checks "easily" enough.
Another thing that would be handy for me and possibly others is if you could host the DM file somewhere where I/We could download it and run it. I am new with DM, but use datalogging all the time to track down issues. There is lots of information in all the PIDs that can help with diagnosis. If not, then I would like to see the critical vehicle information: RPM, MAP, TPS and ECT (although ECT likely isn't a problem) during the run.
A quick rundown of my strategy:
Note! hearing/feeling/smelling things real time would have me altering these steps as I see fit, but generally this would sum it up.
Base line it at idle.
Datalog it running well (ie below and above the problem and where the problem occurs. Have vacuum gauge connected to manifold vacuum.
Fuel pressure gauge connected to rail.
TDC would have been verified and timing checked (maybe early-maybe later depending upon how it "sounds" cranking)
Run the engine and powerbrake the engine. Your TC allows you to run it up to your trouble spots which is handy!
How does the vacuum look? If the gauge starts fluttering/jumping it's a mechanical issue. Valvesprings,lifters or such. If the gauge is just lower than idle (maybe 10-15 I would guess) then I would be skipping over the mechanical and
look at Fuel pressure. Gauge is steady? I would then bleed fuel out of my release while it's acting up and verify no air bubbles from a cavitating fuel pump.
I would then be on to ignition, after performing a relative compression/timing check using my scope. Hook up scope to battery positive/negative. Set amplitude to 2V/Div, timebase to 100mS (to start), Use #1 ignition as synch. Disable fuel (but not spark, let vehicle run/die most likely pulling injector fuse if it doesn't disable coil): Single shot, triggered on negative voltage slope at around 12V. Even current increases as the engine goes to TDC on each cylinder (Compression) would indicate a healthy engine, but more importantly you could see the #1 spark signal in relationship to TDC (should be 0 with bypass disconnected right?
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Ignition: Secondary at coil. Bring the engine up to and through the problem. Hows the signal look, indications of lean/rich cylinder? Shorting on all/some of the cylinders? Is the coil being commanded to fire each time, or is it failing to fire? When it fails to fire, is the voltage high (good power supply and coil didn't go open) or did voltage disappear or drop? (shorting coil or power supply problem.) Look at the coil turn-on does it show a nice ramp with good dwell control or does the waveform show a shorting coil or Ignition module/PCM control issue? If the signal is disappearing when the problem occurs then it's off to the PCM to watch it. Your DM file shows the timing doesn't go to 0, so I would skip the bypass and watch RPM reference (thru the ignition module from the stator) and the EST signal. Do they stay steady (clean square wave) or do they start falling apart or disappearing all together. If they are disappearing then it's pulling the cap off and looking at the stator signal (a little tricky to scope since it's connected internally (I cut open a distributor cap and have a "custom wire harness" to make it easier). If the stator is steady, then the module powers/ground needs to be checked and then it's new module time.
If ignition looks good, I would scope both ignition banks at the PCM. They should be exactly the same with no missing signals or waveform anomolies as well. Also, watch the waveform to ensure battery voltage stays steady and that the ground voltage stays low and doesn't creep up over 200mV or so (indicating a bad ground or abnormally high current draw. I would also be looking for nice injector voltage clipping upon turn-off. Same as the coil current, I would amp clamp the injector harness at the PCM (or actually I'm lazy so I would use the inj fuse) to make sure that each bank of injectors is pulling the appropriate (and even) current with a nice slope to indicate no shorted injectors.
A 4/5 gas analyzer would also be handy to track this down, especially if you could drill (and later seal) a very small hole in the #1 bank. If the HCs stay low (and CO doesn't drop) then that bank isn't your problem. If the numbers are higher after the turbo, then it's bank #2.
You get the picture. I am not trying to toot my own horn, it's just not rocket science and this stuff can be found without all the effort you have put yourself through. The PCMs don't have fast enough processors to catch the many of your potential problems just using a scan tool. You have put a ton of effort into this thing and you deserve it to be fixed. By the way, your cold start would be even easier to diagnose. :tup:
Come to think of it, I'm not the only guy that can do this (although you could drive it on up here to the not-so-frigid north), I've done training in NJ and NY. There are some competent guys in your neighborhood that could scope this out for you and would be up for a challenge. I can contact an instructor I know to give me some names of these guys to run this down for you! PM me if you are interested. After everything you put into it, I bet a guy with the PCM already pulled loose could diagnose this thing in under an hour (and charge you 3 since he is obviously one smart cookie!)
My laptop battery is almost dead, I hope this makes sense and that there aren't too many typos!
